CHAPTER IV
TRAIN SCHEDULES

Having studied in the two previous chapters the important
elements underlying the determination of probable traffic on a
new railway line or upon the extension of an old system, it be-
comes necessary to establish the train schedule. As has been
previously inferred, this is often a question of judgment to be
exercised by the executive head of the road in view of the necessity
of meeting competition. That is to say, the engineer who plans
the details of the train schedule is instructed to arrange for
hourly or half hourly interurban service, as the case may be, or
the headway expressed in minutes or distance between cars in
feet may be specified in the urban system. In both types of
system, the limiting schedule speed is usually stipulated, often
by the municipalities involved. The interurban system is usu-
ally limited to two or more different schedule speeds, the higher
velocities being confined to operation over private right of way
and the lower within city limits or upon particularly dangerous
sections of track such as trestles, drawbridges, and temporary
construction.

Whereas the hours of train arrival and departure are usually
placed in the hands of the public in the form of time tables,
the most convenient and common form for the study of these
data by railway engineers is the graphical chart. Many factors
entering into the proper construction and successful operation of
a road are at once apparent from such a chart or graphical train
schedule. This train schedule is often plotted with time of day
in hours and minutes as ordinates and distances expressed in miles
as abscissae. It is convenient if the ordinates representing the
hours be designated by heavy lines on the coordinate paper and
if the hourly sections be subdivided into sixths or twelfths, rep-
resenting 10 and 5 minute intervals respectively. Upon the
distance scale it is customary to designate the distance between
stations and the location of any points of especial engineering
interest along the line such as branch lines, railway crossings,

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